1. Field of the Invention
The present invention relates generally to equipment for the thermal spraying of powdered materials. More specifically, the present invention relates to an interchangeable nozzle interface for use with a thermal spray plasma gun.
2. Description of Related Art
A variety of thermal spray coatings have been used to protect various types of components. Coatings may provide various benefits such as to resist wear, retard corrosion, control clearances, salvage worn components, resist high temperatures and/or enhance electrical properties. These benefits can differ based on the coating material type and how those materials are applied. One group of spray coatings to which the subject matter of the present invention pertains in particular are those applied via the plasma spray process. This process has been used to apply many different types of coatings in numerous industries.
Each material coating specification requires a specific range of velocity and temperature transferred to the powder particle to achieve the required material properties on the part. Improved consistency and efficiency in the delivery of thermal spray coatings remains an industry-wide goal.
The plasma gun has been used as a process tool in the spray coatings industry due to the wide range of parameters that are achievable with this basic tool. A key element of any plasma gun is the nozzle geometry. Variations in nozzle geometry can allow a plasma gun to provide coating properties at a different temperatures and velocities from the same base equipment. When operators would need to apply a different type of spray coating, they often must use a different nozzle. Thus a single plasma gun with interchangeable nozzles can serve multiple uses and, potentially provide significant equipment costs savings over guns with a fixed nozzle geometry. Generally, prior art spray gun and nozzle configurations were not typically designed with nozzle interchangeability in mind. Prior art configurations were such that the operator would also often need to change the spray gun itself.
However, there are a number of factors that can prove challenging in replacing the a plasma gun nozzle. Plasma spray guns must perform several different functions in order to achieve a successful coating process. Those functions include proper alignment of the spray nozzle as well as sealing of the channel through which plasma gases flow. Also, cooling of the gun nozzle during the spray process is required to prevent overheating. So proper flow of coolant sealing around the nozzle area and adequate sealing of the cooling path is essential. An electrical connection between the nozzle and the plasma gun is also required to serve as the return path for the plasma arc current flow. Precise orientation of mechanical location, electrical connections and water chamber seals must be achieved to obtain the desired spray characteristics.
A standard interface for each nozzle that would assure proper orientation of all plasma gun components with each interchangeable nozzle, while minimizing the risk of human error would be beneficial to the spray coating industry. Optimal orientation could extend the range of performance for a single thermal spray plasma gun. Thus, there remains a need in the art for a standard nozzle interface for a thermal spray plasma gun that provides an optimal, efficient and repeatable nozzle connection for a wide range of nozzle geometries.